INCREASING REV LIMIT
Posted: Sun Aug 12, 2007 2:10 pm
OK: here is what I have found...
In a Bosch 0 280 001 134 3.0 box, you can change the value of a resistor to increase rev limit. Decreasing resistance increases rev limit.
Resistor is #R704 located on the underside of the NON connector board.
1. Remove ECU
2. Remove two case bottom screws
2.5. Remove guts
3. Carefully remove two spring clips
4. Carefully remove THREE retaining screws. This is the board you want to work on.
5. open plastic wire cover(it just pops open)
6. GENTLY flip board over
In top left quadrant, you will see three elevated resistors. SEE PICS. The BIG FAT resistor is the NEW one. It is ~4700 ohms by color bands ( better to use at least 1/2 watt , and this is Gold quality..not that that matters too much..it's probably the best resistor on the board)
http://www.radioshack.com/product/index ... age=family
Anyway, OLD resistor is ~6200 ohms using color bands.
As a double check, NEW resistor is 4600ohms measured resistance (on board) ...
I checked both boards closely and this was the only change I could find. And , this makes sense as only one resistor should be needed to effect peak rev waveform....this allows "overvoltage or over-rev" to occur and does not shut off injectors. I have no other electrical mods to Bosch stuff and can rev to at least 7500rpm...
WARNIG: mod done on 3.0L ECU, although similar, I am not familiar w/2.5's. Also, overrevs can kill your engine..do this at your own risk!!
In a Bosch 0 280 001 134 3.0 box, you can change the value of a resistor to increase rev limit. Decreasing resistance increases rev limit.
Resistor is #R704 located on the underside of the NON connector board.
1. Remove ECU
2. Remove two case bottom screws
2.5. Remove guts
3. Carefully remove two spring clips
4. Carefully remove THREE retaining screws. This is the board you want to work on.
5. open plastic wire cover(it just pops open)
6. GENTLY flip board over
In top left quadrant, you will see three elevated resistors. SEE PICS. The BIG FAT resistor is the NEW one. It is ~4700 ohms by color bands ( better to use at least 1/2 watt , and this is Gold quality..not that that matters too much..it's probably the best resistor on the board)
http://www.radioshack.com/product/index ... age=family
Anyway, OLD resistor is ~6200 ohms using color bands.
As a double check, NEW resistor is 4600ohms measured resistance (on board) ...
I checked both boards closely and this was the only change I could find. And , this makes sense as only one resistor should be needed to effect peak rev waveform....this allows "overvoltage or over-rev" to occur and does not shut off injectors. I have no other electrical mods to Bosch stuff and can rev to at least 7500rpm...
WARNIG: mod done on 3.0L ECU, although similar, I am not familiar w/2.5's. Also, overrevs can kill your engine..do this at your own risk!!